Acoustic diaphragm made of warped elementary surfaces with parallel edges



L. LUMIERE March 17, 1931.

-mous'rtc DIAPHRAGM MADE OF WARIED ELEMENTARY SURFACES WITH PARALLEL EDGES 4 Sheets-Sheet 1 Filed May 13. 1930 L. LUMIERE ACOUSTIC DIAPHRAGM MADE OF WARPED ELEMENTARY SURFACES WITH PARALLEL EDGES Filed May 13, 1930 4 Sheets-Sheet 2 L. LUMIERE March 17, 1931.

ACOUSTIC DIAPHRAGM MADE OF WARPED ELEMENTARY SURFACES WITH PARALLEL EDGES 4 Sheets-Sheet 3 Filed Ilay 13. 1930 March 1931- v 1.. LUMIERE 96,335 ACOUSTIC DIAPHRAGM MADE OF WARPED ELEMENTARY SURFACES WITH PARALLEL EDGBS Filed llay 13, 1950 4 Sheets-Sheet 4 Patented Mar. 17, 1931 UNITED STATES PATENT OFFICE LOUIS LUMIEBE, OF NEUILLY-SUR-SEINE, FRANCE ACOUSTIC DIAPHRAGM MADE OF WARPED ELEMENTARY SURFACES WITH PARALLEL EDGES Application filed Kay 18, 1930, Serial F0. 452,008, and in France June 4, 1929.

My invention relates to an acoustic diaphragm, square or rectangular in shape, made of warped trapezoidal elementary surfaces having parallel edges. Such a diaphragm has the advantage of possessing the rigidity that is necessary for obtaining a high acoustic efficiency.

The invention will be illustrated in the following drawings, in which Figure 1 is a plan view of a paper ring with lines traced on it, said paper ring serving to make the acoustic diaphragm.

Figure 2 shows a part of said paper ring unfolded, after it has been plaited and cut along one radius, the edge of the inside circumference being developed along a straight line as it will be explained hereafter.

Figure 3 is a transverse section on the line ww of Figure 2 of an element consisting of a part of a ring.

Figure 4 is an end view corresponding to Figure 3.

Figures 5 and 6 are respectively an elevation and a transverse section of an acoustic diaphragm obtained by assembling together two parts of a ring similar to that of Figure 2.

Figure 7 is a sectional view showing how some points of the edge of the diaphragm are secured to the frame through cork or felt washers.

Figures 8, 9 and 10 show, on a larger scale, the middle part of the diaphragm thus obtained, in the vicinity of the plaited edges which are assembled together.

Figures 11 to 14 relate to different forms of the diaphragm.

The acoustic diaphragm, according to my invention, is made of trapezoidal elementary surfaces a, Figure 1, limited by equidistant radiuses of a ring, the proportions of the inner and outer diameter of which may vary according to the warping conditions which give the necessary rigidity to the elements, when the latter have been folded and developed. Said elementary surfaces are next folded, and the ring is cut into parts, which are developed in such a manner that the inner circumference of said parts is disposed along a straight line. The length of said line depends on the dimensions of the diaphragm.

The parts of rings thus developed are, in horizontal projection, rectangular in shape, and the edges of the folds, on account of the 1gvarping that they are given, are slightly ent.

The relative dimensions of the inner and outer diameters of the ring ma for instance, be chosen in the proportion of 1 to 2, and in that case, the folds, on the side of the larger bases of the trapezoidal elements, are at an angle of to each other.

In order to obtain the acoustic diaphragm, two elements such as the one shown in Figures 2, 3 and 4 are assembled by placing them side by side, so that the folded large bases overlap each other, as it is shown on a larger scale in Figures 8 and 9; and said overlapping parts are glued together. The common glued part is then pierced through, so as to enable to insert, in a direction perpendicular to the edges, a rigid barb I), made of aluminium, wood or any other material, thin and rather wide, which is stuck to the folded elements by means of small paper bands or better of a cellulosic varnish.

It is through said bar, which is driven by its middle part, or by any other part, that the diaphragm is connected to the movable rod of an acoustic or electromagnetic vibrator.

Said acoustic diaphragm may be mounted in a frame 0 made of wood or any suitable material, and fixed in position through cork or felt washers d which holdits straight edges in suitable points, so as to avoid any parasitic vibration.

Said diaphragm may be made of drawing paper, which subsequently, will be coated or not with a suitable varnish or any other material. It is also possible to use, for making the diaphragm, a very thin laminated sheet of aluminium, about 0.01 millimeter thick, or a sheet of any other similar light metal or alloy, lined with a sheet of a suitable paper, weighting, for instance 120 grammes by square meter, or of any other suitable substance.

When the diaphragm according to the invention is made with a very thin laminated sheet of metal, lined with paper, a very good ISO Figures 5, 6, 8 and 9, one may use a tube of light metal or any other suitable material, passingthroughthe folds of the diaphragm, in the same way as the rod.

Figures 11 and 12 show this embodiment of the invention.

In these figures, the partsof rings are,

placedin the same way as above; their folds slightly overlap each other, and are glued to gether; they are connected together by means of a tube 12 made of a light metal, or any other material, which passes through the folds; As explained above saidtube is actuated by the vibrations-of the motor and transmits said vibrations to the diaphragm.

Instead of actuating the rod or tube 6 or 6 by a -single motor, it-may be advantageous to actuate-said rod or tube by several motors connectedto several points of the rod ortube. Forthis purpose, said points will be so dis- 26itributed along'therod or tube-as to set in vibration parts of the diaphragm havingequal areas. For instance, in the case of Figure 13, rod 6 is actuated'in two points Aand B, which set in vibration, parallelly, equal areas Z and'm, as indicated, in'dotted lines, by their diagonals, and-in the case of Figure 14, rod bis actuated in three points A, 13,6, which set in vibration equal areas Z,- m, 1. Of course such points could be still multiplied.

While I have disclosed preferred forms of my invention, I do not wish to be limited thereto, as there mightbe changes made in theconstruction, dispositionand form of the parts without departing'from the spirit of my invention, as comprehendedwithin the" scope of the appended claims;

What I claim is 1. A method for obtaining an acoustic diaphragm which consists in taking a ring of a thin material, in folding said ring along equidistant radiuses, in cutting it into elements of given length, invunfolding said elements so that their side corresponding to the inner circumference of the ring is applied alonga straight line and the edges of; their folds are all parallel, in applying two such elements one-against the other along their folded bases so that they slightly overlap each other and in gluing them together, in passing through'all the folds of the overlapping part arigid'piece and in fixing said piece to the folds, so that said rigid piece serves to transmit. the vibrations to the diaphragnn 2. A rectangular acoustic diaphragm comprising two folded elements having each a straight sideand a'folded side and edges of folds parallel between themselves, means'for" securing together the folded sides of said elements, a rigid piece passing through the foldsiofboth elements,- means for fixing said metallic tube'p'assin'g'through the folds of both elements whereby the vibrations are transmitted to the diaphragm, means for fixing said tube to the elements, washers for holding the straight sidesofthe elements, and a frame for supporting said washers.

l. A rectangular acoustic diaphragm comprising two folded elements made of laminated aluminium having each a straight side and a folded side and-edges of their folds parallel to one another, means for securing together the folded sides of said elements, ,a' metallic tube passing through the folds ofboth elements whereby the vibrations are transmitted to the diaphragm, meansfor fixing said tube to the elements, washersfor holding the straight sides of the elements, and a frame for supportingwsaid washers.-

5. A rectangular acoustic diaphragm comprising two folded elements made of laminated aluminium having each a straight side and a folded side and the edges of their folds parallel to one another, means forsecuring together thefolded SlClBS'Of said elements, a

tion in several points, means for fixing said tube to the elements, cork washers for-holdingthe straight sides of the elements, and a frame for supporting said washers;

6. A rectangular acoustic diaphragm comprising two folded elements made of'lami nated aluminium having'each a straight side and a folded side and edges of their folds parallel to one another, a paper lining on each folded element, means for securing together the folded sides of said elements, a metallic tube passing through the folds of both elements whereby the vibrations are transmitted to'the diaphragm, means forfixing-said tube to the elements, washers for holding the straight sides of the elements,

and a frame for supporting saidwashers.

. In testimony whereof I have. signed this specification.

LOUIS LUMIERE; 

